Last week, I discussed
and offered some pointers to how you could get
started along with reviews of a couple of books that can help. This week I
want to back up a bit and talk about how you can get started
First, though, I do need to address the question of what makes a
different from a regular audio file posted on a website. On a purely
technical level, nothing is really different about the audio file.
In fact, if you just want to listen to a podcast to see if it is something
you would like to listen to on a regular basis, the best bet is often to go to the podcast
website and simply download a recent episode and play it in your media
What is different is the way in which the audio file is normally retrieved. Rather
than being something you click on, download, and play, you subscribe
to the podcast RSS feed. This works by virtue of the fact that Dave Winer
added an element called an Enclosure to RSS 2.0.
Note that the enclosure element is actually not specific to audio: it can be used for
pretty much any media element including video or images.
The beauty of this solution is that you simply need to subscribe to
whichever podcasts interest you and then listen to them whenever new shows
arrive - and whenever you feel like playing them. No need to check web
sites for updates. No need to be online to listen to a streaming feed.
Many people have referred to podcasting as "TiVo for audio" or
"timeshifting radio" and indeed it very much works that way.
So in order to subscribe to podcasts, you need some software tool that
can: a) handle RSS feeds; and b) interpret the RSS enclosure tag to
download the media automatically for you. At a base level, that is pretty
much all you need and the software that does this is often called either a
"podcatcher" or "podcast aggregator". Of course, the programs out there
don't simply do the base. They add the ability to easily manage your
subscriptions, schedule the interval to check (ex. setup an appropriate
cron job), manage the downloaded files, etc.
Linux users have the choice, of course, of podcatcher software in pretty
much any language and with or without a GUI. A search on "podcast" at
sites such as SourceForge or freshmeat will turn up a variety of
choices in various states of development. Some of the prime contenders
iPodder - For someone just getting started who wants a GUI, my
personal recommendation would be to start out with iPodder (also called the "iPodder
Lemon" because of its logo). Being python-based,
iPodder is cross-platform and is heavily-used within the Windows and Mac
worlds. Linux users receive the benefit of all that usage/testing and have
a robust program to use. Screenshots
are available if you would like to see what it is all about.
BashPodder - For the text-inclined, BashPodder
provides the functionality you need via a basic shell script. Simple,
easy, and a breeze to extend. In fact, the site contains a wide range of
user-contributed extensions and customizations. Additionally, for those who want the
power of the shell but still with a GUI, there is BPConf that
allows you to easily configure BashPodder.
jpodder - Another interesting choice is jpodder, a Java-based cross-platform
podcatcher. Like iPodder, it is GUI-based
and has a range of features.
Other choices - There are a range of other options (and readers
are encouraged to leave their recommendations as comments), including:
A reader last week also commented that they were able to have Apple's
iTunes program running on their Linux system using CrossOver Office. In
any event, you need to have one of these programs installed to have the
simplicity of subscribing to podcasts.
The Next Step
Once you have the software installed, you need to find podcasts to which
you can subscribe. Some of the podcatchers, such as iPodder, include a
built-in directory. Even with such a directory, though, you'll probably
want to check out some of the directory sites. More keep appearing on a
daily basis, but some of the major sites include:
Typically all you need to do is find the URL for the show's RSS feed and
then enter it into your podcatcher software. Some programs allow
drag-and-drop... but in any event that's it... you are now subscribed and
will start to receive new shows. (Some podcatcher software will download
the most recent show and then all new shows - some software will download
all shows available in the feed.)
Happy listening! And please do feel free to leave comments to this
article about your favorite podcasts - or feedback about various podcatcher
Comments (2 posted)
There are a lot of PostgreSQL-derivative projects in the news lately.
In May we looked at the EnterpriseDB
project. The Bizgres Project
released their 0.6 release last week
, with a few new features of interest to organizations using PostgreSQL for data warehousing and business intelligence.
The Bizgres project was launched in April of this year. It is based on the PostgreSQL project, with development sponsored by Greenplum, which also uses the Bizgres source code in its DeepGreen offering. Josh Berkus, who works for Greenplum and is a member of the PostgreSQL core team, talked to us about the Bizgres release and the plans for the project.
The 0.6 release has two features of interest that are not currently found in PostgreSQL. The first is a patch that speeds up bulk loading of text data. Berkus said that the patch "speeds up bulk loading of text data by refactoring some of the bulk loader code."
The other feature is an improvement in temporary table creation. When tables are created using the "CREATE TABLE AS SELECT" statement, transaction logging is bypassed which can provide major benefits in performance -- in effect, a kind of "scratch" table that can be used to hold a copy of data that is being worked with without logging transactions. Berkus said that the Bizgres team is planning on expanding the capability to include the ability to bulk load into a "scratch table" but the current feature does not allow that.
With so many PostgreSQL-derived projects available, some may wonder if the project is forking. He said that Greenplum plans to contribute its features back to the PostgreSQL project, but that the timing of PostgreSQL releases made it hard to get the features that interest Greenplum and its customers into mainstream PostgreSQL in a timely fashion:
Feature freeze for 8.1 was July 1st, that was the last day for consideration of patches for 8.1, and for that matter, if you introduced a major patch on July 1 that hadn't been discussed, there's very little chance it'd be introduced [in the 8.1 release of PostgreSQL]. Much of the stuff [in Bizgres] has bad timing, and would have waited for 8.2.
Since PostgreSQL 8.2 is currently slated for summer of 2006, there is a distinct advantage in creating a derivative distribution of PostgreSQL to allow Greenplum and the Bizgres Project to push its features out to its users earlier. Berkus compared this to Linux vendors like Red Hat backporting features from the 2.5/2.6 kernel series to the 2.4 series while 2.6 was still in development. He also compared Bizgres to embedded Linux or Real Time Linux, "in that we're focusing on a distribution of PostgreSQL entirely focused on needs of people running data warehouses or doing business intelligence." Users outside those profiles, said Berkus, probably don't want to consider Bizgres or DeepGreen at all.
He also said that the Bizgres project is focused only on Linux, Solaris and Windows, as opposed to all of the platforms that are supported by the PostgreSQL project, which produces fewer platform compatibility issues for Bizgres.
Berkus allowed for the possibility that Bizgres could have features that do not make it into mainstream PostgreSQL, if they were of benefit to data warehouse applications without providing a benefit to general performance, but that he wasn't aware of any features under consideration that would fit that category.
As for licensing, Berkus said that anything developed by Greenplum for Bizgres would be available under a "BSD or analogous license."
We want to permit commercialization. Our goal, overall is to make it the standard in data warehousing and the BSD license is the best to choose. It eliminates any legal concerns that someone might have about adopting your software.
He also said that he wasn't concerned about other companies snapping up Bizgres' technology. According to Berkus, the major vendors like Microsoft, IBM and Oracle, "already have technology of their own that they have investment in, and they're unlikely to abandon theirs... and if they did [take Bizgres features and make them proprietary] it would be enough of a moral victory that it would be worth it."
Given the number of companies working on PostgreSQL distributions, it should be interesting to see how many of the improvements flow back into the main project, and whether the various companies can avoid straying too far from the main project. It should also be interesting to see whether the Bizgres project gains much steam as an independent project. The mailing list traffic isn't particularly heavy yet, but the project is still very new.
For users who are interested in trying out Bizgres, the 0.6 release is available as source code or binaries for Solaris 10 or Red Hat Linux.
Comments (1 posted)
The much awaited "maxi" DVD edition of Knoppix
4.0 was presented at the Linux
Tag conference in Karlsruhe, Germany last week. As usual, this was a
special edition and not a public release, but it didn't take long before
the ISO image hit some of the popular BitTorrent download sites and it was
even spotted on a few FTP servers a few days later. The reason for the high
demand is not hard to understand - Knoppix 4.0 is the largest live Linux
DVD ever produced, with a great collection of "the best open source
software" available today.
First, some numbers. The size of the single-layer compressed DVD image is
4,122 MB. It contains over 9 GB of software in the form of 2,663 Debian
packages providing more than 5,300 individual programs. Most of them come
from the recently released Debian 3.1 "sarge", but there are several
noteworthy upgrades, such as KDE 3.4.1. KDE is still the default desktop,
but Knoppix 4.0 now contains ten other desktop environments and window
managers, including the complete GNOME (2.8.1) and XFce (3.8.16 and 4.0.6),
and even some exotic ones, such as LarsWM, Openbox, and RatPoison. Booting
this DVD on a 4-year old 1.4 GHz Pentium 4 system with 384 MB of RAM took
just under 8 minutes (from the GRUB boot prompt to KDE); for comparison,
booting the Knoppix 3.9 CD on the same system took only about 3.5 minutes.
It needs to be mentioned that, starting from version 4.0, Knoppix will be
split into two editions - "maxi" DVD and "light" CD. The light edition
will essentially be the same Knoppix live CD that we have come to love and
appreciate over the last couple of years, except that all development
software will be removed and replaced with more general desktop
applications. The public release of Knoppix 4.0 is expected within the next
few weeks, with the "maxi" DVD and "light" CD editions appearing
The Knoppix 4.0 DVD contains many of the most popular open source software
packages for the desktop, server, office, graphics, multimedia, and
development. Compared to the live CD edition, users now have a choice of
KOffice (1.3.5) and GNOME Office (AbiWord + Gnumeric), in addition to
OpenOffice.org (a recent beta of the 2.0 series). On the server side of
things, both Apache 1.3 and 2.0 are present, and, unlike the CD edition,
the DVD also includes PostgreSQL 8. Some other interesting packages that
have been missing from all recent Knoppix CD releases include Blender,
Eclipse, GnuCash, Mozilla, LyX and teTeX. One downside of the DVD is that,
with so many applications included, the standard Debian menus tend to be
badly cluttered and poorly organized; as an example, the "Internet" submenu
contains a total of 76 items, while the "System" submenu contains 88 items!
Besides adding new packages, what else is new in Knoppix 4.0? In the absence
of any changelog we had to dig around the menus and file system to see what
exciting things are hiding under the bonnet. The DVD has retained the
Unionfs file system so extra packages can be installed on the fly - either
from Debian repositories with apt-get or the newly included Synaptic, or
via the web-based Klik installer,
which also includes some non-free packages. A new feature is the ability to
switch between the 11 desktop environments through a "Restart KNOPPIX
Desktop" utility. Also, the DVD now contains a lot more documentation in
HTML and PDF formats, including the excellent 133-page Knowing
Knoppix and m23 Software Distribution guides.
There seems to be an increasing level of collaboration between the
developers of Knoppix and other Knoppix-derived live CD and DVD projects.
The Kanotix developers
contributed some DSL network configuration and hard disk installation code
(due to data decompression, a partition of at least 12 GB in size is
required for installing the DVD edition of Knoppix 4.0 on the hard disk).
Much of the newly included scientific and statistical software was accepted
from the Quantian
and Paipix live DVD projects,
while a lot of educational software found its way into Knoppix from Freeduc, a distribution designed
Although providing a large number of applications on the DVD should please those
users who missed some important pieces of software on the earlier CD
editions, the size of the DVD presents its own set of problems. We have
already mentioned the unsightly and difficult-to-navigate menus, but a
potentially more annoying problem is the general sluggishness of the system
while it runs from the DVD. Maybe a more modern DVD drive would be able to
launch software packages in a speedier manner, but we were not impressed
with a delay lasting several minutes after clicking on a PDF file in
Konqueror. Likewise, OpenOffice.org Writer took 150 seconds to launch. Even
navigating the menus was painfully slow, much slower than any of the CD
editions. Of course, once an application is cached in the memory it starts
a lot faster, but the first run of any large software package will likely
test your patience.
This brings in the question about how useful a 4 GB Knoppix live DVD really
is. Although it is easy to get excited over all the goodies available at a
mouse click, many people will undoubtedly be put off by the long boot
times, poor system responsiveness and cluttered menus. After having played
with the system for a few minutes, we found ourselves craving for the much
leaner and faster Knoppix CD - although not nearly as full-featured as the
DVD edition, it contains enough applications to satisfy the majority of
users. Whether you use Knoppix as a rescue CD, carry it around to boot
computers in Internet cafes, or employ it to demonstrate Linux and open
source software to interested parties, the CD edition of Knoppix will
probably remain a more practical tool than the more complete, but also more
sluggish DVD edition.
Comments (9 posted)
Page editor: Rebecca Sobol
Inside this week's LWN.net Weekly Edition
- Security: PEAR XML_RPC remote code execution vulnerability
- Kernel: A couple of graphical git front ends, Looking at inotify again,
2.6.13-rc2 kernel released, stable kernel 22.214.171.124.
- Distributions: Yellow Dog Linux 4.0.1 and Y-HPC; Trustix Secure Linux 3.0; grml-small
- Development: Track eBay bids with JBidwatcher, Samba3 Compendium, new CUPS manual,
new versions of HSQLDB, bogofilter, MailStripper, SSL-Explorer, Nvu,
Snd, Mammut, Ceres, Electric, XCircuit, Cyphesis, GIMP, Laffer, Ghemical,
VLC media player, JBidwatcher, GNU Classpath, Hermes, SBCL, pyc.
- Press: ESR on the GPL, European Software Patent Directive Defeated,
JavaOne 2005 coverage, Where 2005 conference, Linux on mobile phones,
Vienna Chooses KDE, SAP on Linux.
- Announcements: Red Hat Quarterly Results, SGI teams with IBM, VA Linux Business Forum,
YAPC::NA::2005 proceedings, ILC 2005 coverage, Indie Games Con,
UKUUG Linux 2005, Summer of Code projects.